The present invention relates to the general field of marking mechanical parts.
A field of application of the invention is that of marking aviation parts, and in particular parts for aviation turbine engines in order to enable them to be identified and authenticated.
In the aviation field, it is known to put a serial number on certain engine parts (e.g. in the form of a hexadecimal base code or in the form of a Datamatrix code), thereby enabling such parts to be identified (they are said to be “marked”). Using such a number, it is possible to know exactly that a part is authentic and to know its origin.
Marking is particularly desired for the blades of turbines and compressors in aviation turbine engines. Blades are critical replacement parts for which it is important to know their exact origin in order to take account of the influence of replacing such parts on the lifetime of the turbine or compressor in question.
Parts, and in particular turbine or compressor blades for an aviation turbine engine can be marked in various ways. It is thus known to perform marking by means of a laser that makes in imprint in the part for marking over a plurality of passes by removing material. It is also known to perform marking mechanically with the help of a hammer or a pneumatic piston that, by imparting successive impacts, enables a serial number of to be marked on a part. It is also known to perform marking by means of a manual or automatic milling machine.
Marking techniques that rely on the principle of removing material or of deforming the part for marking so as to place the desired serial number thereon present a manifest drawback for the soundness of the material of the part that is to be marked. Specifically for a part that is made as a single crystal of metal alloy, deforming or removing material can lead to localized recrystallization or to an irreversible defect in its microstructure.
Furthermore, with turbine or compressor blades, marking by those conventional techniques is generally performed on the roots of the blades. Marking a portion of the blade that is exposed to gas (e.g. its airfoil) cannot be envisaged: the gas sweeping over the surface of such a zone runs the risk of erasing the serial number by erosion/oxidation, or indeed by tearing out material. Furthermore, a crack starter at the location of the marking might appear as a result of vibratory fatigue.
Unfortunately, marking a blade on its root raises the problem of the root of a blade being a zone that is hidden once the blade is assembled, such that identifying the blade becomes impossible once it has been mounted in an engine.